Quote Originally Posted by Rjk View Post
if you have convincing data I'd love to read it.

in every other place in the world a reduction in speed results in a reduction in deaths so why would Wales be any different?
Back to the accident data spreadsheet from 2022.

Number of accidents with casualties:

20mph speed limit area - 192
30mph speed limit area - 1691

Stands to reason - 37.4% of roads in 2021 had 30mph speed limits, 2.5% had 20mph speed limits. There were 870km of 20mph road across Wales and 13,085km of 30mph road.

Kilometers per accidents with casualties:

20mph speed limit area - 870/192 - per 4.53km
30mph speed limit area - 13085/1691 - per 7.74km

Number of accidents with casualties where those casualties were serious or fatal:

20mph speed limit area - 40 - 40/192 = 20.8%
30mph speed limit area - 380 - 380/1691 = 22.5%

Number of accidents with casualties where there were fatalities

20mph speed limit area - 40 - 2/192 = 1.0%
30mph speed limit area - 380 - 27/1691 = 1.6%

It's interesting that there was a higher proportion of accidents on 20mph roads where there were casualties, than on 30mph roads. The reduction of serious casualties and fatalities dropping from 30 to 20mph is nowhere near the levels being exaggerated.